docs: def random(self, length=None):
          """
          Generate and return a cryptographically-secure short random string
          of the specified length.
          """
          if length is None:
              length = self._length
  
          random_num = int(binascii.b2a_hex(os.urandom(length)), 16)
          return int_to_string(random_num, self._alphabet, padding=length)[:length]